Rai is the main currency of Castland. It can be found all throughout the game, mainly by defeating enemies and smashing boxes or treasure chests. Some side quests also offer Rai as rewards.
There are three types of Rai: bronze, worth 1 Rai; silver, worth 3 Rai; and gold, worth 5 Rai. Bronze Rai are the most common type and can always be seen dropped by defeated enemies or smashed containers. Silver Rai are less common and only sometimes spawn from enemies and boxes. Gold Rai are the rarest of all and can only be found in treasure chests.